It is well known that timbers in the forests almost never grow perfectly straight. Each timber has its own specific shape which is the result of small natural curvatures of the trunk along its length. These curvatures create a resulting curvature hereinafter called "the curvature" which may be small or negligible on most timbers but very important on many others. While most of the curvatures are the results of nature, some may also be the result of bad transportation or storage conditions.
Once the timbers are cut down, many of the resulting logs are used by the sawmill industry for transforming them into studs, beams or similar products. The logs are first brought to a location called the cant mill which may be in the sawmill itself or not. The logs are then transformed into cants by a chipping canter upon removal of outside wood portions on usually four sides with slabbing heads for obtaining cants with rectangular cross-sections. The slabbing heads transform these wood portions into wood chips and dust, which can later be used for other purposes, particularly for producing wood pulp.
In the past, the curvature of the logs was not an important factor because the timbers were generally old growth trees bigger than the ones found nowadays. The curved portions were then simply machined off and the resulting straight cants were still having a very large cross-sectional area and a very suitable length. As the timbers become smaller and the operating costs higher particularly because of the remote locations of modern logging sites, the systematic rejection of small curved timbers is no longer possible. Curved sawing techniques are now increasingly used by the sawmill industry for producing studs and beams from curved cants. The curved studs or beams are straightened thereafter by a suitable process.
In spite of the increasing economical value of curved logs, no suitable chipping canter has yet been developed for optimally machining those curved logs.